1. Field of the Invention
The present invention relates to an anti-backflow valve for preventing backflow of water into a water supply line.
2. Description of the Prior Art
Conventional anti-backflow valves comprise two check valves connected in series and a relief valve for venting the connecting passage between both check valves. Such a backflow prevention valve is shown in U.S. Pat. No. 4,207,915. This known backflow prevention valve comprises an offset vertical and parallel arrangement of all internal valves so that upon removal of a cover those valves can be easily replaced or may be serviced, respectively, without removing the whole backflow prevention valve unit from the supply line. The check valves are of similar design, but there are different mounting means provided for each check valve so that no danger of incorrect insertion exists. However, that known backflow preventer has its relief valve offset from the plane in which the two check valves are arranged which results in a bulky valve unit of unsymmetrical design.